[Plugin: WordPress Ultra Simple Paypal Shopping Cart] Discount coupon for cart

Just wondering if you’re going to add this discount coupon option for your cart? I saw on your plugin that you were working on it for a few months, but then the updates started. I really like this plugin, however I really need to have that discount coupon option.

http://wordpress.org/extend/plugins/wp-ultra-simple-paypal-shopping-cart/